RFC 1172 (rfc1172) - Page 2 of 38

Point-to-Point Protocol (PPP) initial configuration options

RFC 1172                  PPP Initial Options                  July 1990


2.1.  Maximum-Receive-Unit

   Description

      This Configuration Option provides a way to negotiate the maximum
      packet size used across one direction of a link.  By default, all
      implementations must be able to receive frames with 1500 octets of
      Information.

      This Configuration Option may be sent to inform the remote end
      that you can receive larger frames, or to request that the remote
      end send you smaller frames.  If smaller frames are requested, an
      implementation MUST still be able to receive 1500 octet frames in
      case link synchronization is lost.

   A summary of the Maximum-Receive-Unit Configuration Option format is
   shown below.  The fields are transmitted from left to right.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Type      |    Length     |      Maximum-Receive-Unit     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type

      1

   Length

      4

   Maximum-Receive-Unit

      The Maximum-Receive-Unit field is two octets and indicates the new
      maximum receive unit.  The Maximum-Receive-Unit covers only the
      Data Link Layer Information field but not the header, trailer or
      any transparency bits or bytes.

   Default

      1500









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